This invention relates to a metering valve for drop feeding of a liquid lubricant.
U.S. Pat Nos. 4,062,424 and 4,096,924, owned by the common assignee of the present invention, disclose metering valves for drop feeding of liquid lubricant at relatively slow feed rates, generally in the range from even less than 5 drops per minute up to about 15 drops per minute. While the porous rod metering valves of the patented construction were considered an improvement over the needle valves which due to silting become inconsistant and even erratic in a relatively short period of time, the porous rod valves, too, proved to be sensitive to impurities and additives in the lubricant and to changes in the formulation thereof. It is generally an object of this invention to provide a metering valve which will drop feed a liquid lubricant with substantial consistency over a reasonably long period of time.